In a system that supplies fuel to a direct injection type engine, a low pressure fuel is drawn by an electric pump from a fuel tank, and supplied to a high pressure pump driven by the engine. A high pressure fuel discharged from this high pressure pump is then pumped to a fuel storage unit. Then, high pressure fuel is supplied from this fuel storage unit to each of a plurality of injectors.
For example, as described in JP 2013-32750 A, a high pressure pump includes a pressurizing chamber and a plunger. The pressurizing chamber includes an inlet and an outlet for fuel, and the plunger reciprocates within the pressurizing chamber. The pressurizing chamber is also referred to as a pump chamber. In addition, the high pressure pump includes a valve, a valve bias spring, and an electromagnetic actuator. The valve acts as a flow regulator by opening and closing a fuel passage connected to the inlet. The valve bias spring biases the valve in a direction that causes the valve to close the fuel passage (hereinafter, referred to as a closing direction).
In addition, the electromagnetic actuator causes the valve to move, i.e., to open and close. The electromagnetic actuator includes a movable rod and a solenoid. The rod is biased by a spring to push the valve in an opening direction opposite to the closing direction. The solenoid, when energized, attracts the rod in a direction opposite to the pushing direction of the rod on the valve.
According to this type of high pressure pump, during a rise period where the plunger is rising from bottom dead center to top dead center, the solenoid is energized to close the valve. Accordingly, the fuel in the pressurizing chamber is discharged from the outlet to the fuel storage unit. In addition, during the rise period of the plunger, even if the solenoid is deenergized after the valve closes, the valve is maintained in an open state by the fuel pressure in the pressurizing chamber.
However, according to this type of high pressure pump, if the closed valve moves in the opening direction and forcefully collides with a stopper placed at an end position in the opening direction, an unpleasant sound may occur.
For this reason, according to the controller described in JP 2013-32750 A, during the rise period of the plunger, after the valve closes due to energizing the solenoid, the solenoid is then deenergized. After that, when the plunger begins to fall from top dead center, the solenoid is reenergized. Here, an opening actuation direction of the movable rod refers to the direction in which the rod pushes the valve to cause the valve to open. By reenergizing the solenoid, the movement speed of the rod in the open actuation direction is reduced. Accordingly, the speed at which the valve collides with the stopper is reduced, and the resulting noise is reduced.